Description of the Prior Art
Modern high-speed electrographic copiers make document reproductions by exposing an electrically-charged photoconductive member to a light image of the document. The light image selectively discharges the photoconductive member to form a latent image charge pattern on the member corresponding to the document. An oppositely charged developer material is brought into contact with the latent image to develop the image. The developed image is then transferred to a receiver sheet and fixed to the sheet by heat and/or pressure to yield the desired copy.
The developer material includes a resinous powder known as toner. If all the toner is not transferred to the receiver sheet, the residual toner may scatter throughout the copier and contaminate other components within the copier. It is therefore standard practice to include apparatus for cleaning the photoconductive member immediately after image transfer from the photoconductive member to the receiver sheet.
Typical cleaning apparatus for a photoconductive member are shown and described in U.S. Pat. Nos. 3,615,813; 3,838,922 and 4,099,861. Briefly, one of the most commonly used cleaning apparatus includes a rotating bristle brush which sweeps residual toner from a photoconductive member. This brush is mounted in a manifold housing defining a chamber having an outlet port. The chamber encloses the rotating brush except for an opening adjacent to the photoconductive member through which the brush extends for contacting the photoconductive member. A source of vacuum connected to the outlet port establishes an airflow which transports toner from the brush and chamber where it is subsequently removed by filter apparatus.
In practice, toner often times is not completely removed from the chamber of the cleaning apparatus due to uneven airflow over the length of the brush and within the chamber. This uneven airflow causes nonuniform cleaning of the rotating brush and results in deposition of the toner in areas of the chamber where the airflow velocity becomes too low to transport toner. Eventually, airflow and cleaning efficiency can be reduced to a point where residual toner material is left on the photoconductive member and is transferred to subsequent receiver sheets resulting in copies with ghost images or high density background.